Process for refining vegetable oils and the like



Patented Aug. 9, 1938 UNITED STATES PATENT OFFICE PROCESS FOR. REFINING VEGETABLE E8 AND THE LIKE Siegfried Leonard Langedijk and Willem illoltot, Amsterdam, Netherlands, assignors to hhell Development Company, San Francisco, @alift, a cor-ration oi Delaware No Drawing. Application May is, may, Serial No. 142,885. In the Netherlands May 25, 11936 M ills.

provision of a method for reducing the acid hum-- ber and/or color of ester type oils, etc., to a veryv 0 low value without substantial loss or consumption oi" refining agent. i

The process of our invention essentially comprises extraction of the oil, fat or wax to be refined with one or more hydrated amines, that is basic aliphatic and/or aralkyl amines which have water associated therewith. We have found that such amines, whether in aqueous solution or not, i. e., whether containing only water dissolved in the amine or anexcess thereover, have many advantages over fatty oil refining agents which have been suggested heretofore. Our tests have shown these amines to be very edective in the removal of undesirable components, particularly free iaty acids, aldehydes, mucines, odorants and coloring matter, from animal and vegetable oils, fats and waxes, while leaving unaifected the fatty acid ester and glyceride content due to the exceptionally low solubility of these desirable components in. hydrated amines.

The corresponding unhydrated amines are not suitable due to their miscibility with fatty oils containing free fatty acid as well as the very rapid amidation whch takes place when they are so used. Amines containing .hydroxyl groups are also less suitable than the hydrated amines used in the process of our invention. For example, the extracts obtained in our process are more easily and satisfactorily de-acidified than is the case when ethanolamines are used as extractants, that is, our solvents are more readily and completely recoverable in condition for re-use. The loss of solvent thru undesirable side reactions, especially amidation reactions, is also lower when hydrated amines arev used. Furthermore, by the 46 use of hydrated amines it is possible to achieve a more nearly complete removal of acids from contain water homogeneously taken up by the amine, that is, amines which have been hydrated. By hydration oi. amines is meant dissolving water in amines, irrespective of the form in which the water occurs in the amines. Moreover, the amines should, preferably, be sufiflciently soluble in water to have a favorable distribution ratio between water and fatty oil or the like. Typical of such amines which are suitable in the process oi our invention are the hydration products of alt phatic amines, including primary mono-amines such as ethyl amine, isopropyl amine, tertiary butyl amine, diethyl carbylamine, neopentyl amine, etc., secondary mono-amines as dimethyi amine, methyl ethyl amine, methyl secondary butyl amine, di-isopropyl amine and the like; tertiary mono-amines, e. g, trimethyl amine, dimethyl ethyl amine, methyl ethyl propyl amine, etc.; diamines such as ethylene diamine, propylene dlamine, trimethylene diamine, cadaverine, piperazine, and the like, and polyamines such, for example, as diethylene triamine and higher homologues and analogues, as well as arallzyl amines, such as benzylamine, phenylethylamine, benzyl methyl amine, benzyl dimethyl amine, etc. Hydration products of the corresponding halogen substitution products, such as beta [bromoethyl amine and the like may also be used. These hydrated amines may be used individually,

as varying mixtures of group members, or in admixture with other suitable materials which may themselves be solvents for one or more components of the material being refined, as with ammonia and/or alkylolamines, etc., or which may behave solely as a diluent.

The amount of hydrated'a'mine used and the proportion of water to amine may be varied widely in the process of our invention. Good results have been obtained using about 1 mo]. of

-water per mol. of water-free amine. Excessive amounts of water are preferably avoided, however, not only because theyunduly increase the cost of solvent recovery but also because in some cases they lead to emulsification difllculties. We have found the range of about 1 mol. to about 2 mols of water per mol. oi water-free amine to be suitable, altho somewhat lower or higher ratios may be successfully used.

We preferably employ low boiling amines as their recovery by distillation is more economical, but may use amines which are normally solid provided they form liquid mixtures with water at the temperature used for refining. In all cases amines which may be distilled, suitably in vacuo or with steam, are preferred.

Depending upon the nature of the material to be refined and of the amine chosen as refining agent, our process may be carried out at ordinary, reduced or elevated temperatures while in all cases avoiding dehydrating conditions and most preferably using temperatures not exceeding 100 C. The refining may be effected batchwise, intermittently or continuously. Counter-current extraction principles may, for example, be advantageously applied. The fats, oils or waxes may, where desirable, be first taken up in a suitable solvent or dispersing agent.

One method of carrying out the process oi. the invention, for example, comprises adding a quantity of the chosen hydrated amine to the material to be refined and mixing mechanically to insure intimate contact of the two phases. then separating the phases as by stratification and decantation or centrifuging or the like. One phase will then represent refined product while the-other phase will be composed of refining agent containing extracted impurities. Due to the wide diilerence in specific gravity, usually, of these phases, the separation is generally quite simple and easy. After separation of the phases, the refining agent may be recovered from the extract, for example, by distillation, preferably fiash distillation, and may be'used again for extraction of the same or anotherbatch of material. The refined product may be stripped of any refining agent still present and of extract components by water washing or the like. Alternatively the recovery of hydrated amine from the rafiinate may be by vacuum or steam distillation, or blowing with an inert gas or other suitable method.

For the purpose of making our invention more clear it will be illustrated by typical examples showing its application to the refining of cocoa butter and palm oil, but it will be understood that this implies no limitation on our process which is equally applicable to the refining of a wide variety of other ester-type oils, fats and waxes, including, for example, cottonseed oil, corn oil, olive oil, train oil, cocoanut oil, soy bean oil, tallow, wool fat, spermaceti, carnauba wax, palm wax, Japan wax, menhaden oil, herring oil, sardine oil, neats-foot oil, linseed oil, sesame oil, and the like.

Example I 125 g. cocoa butter, acid figure 1.8, is shaken at 60 C. for minutes with 6 g. ethylene diamine monohydrate; the. mixture is then centrifuged and the upper layer (the rafilnate) is washed out with water and dried. The product has an acid figure of 0.11.

The ethylene diamine may be recovered from the extract by flash distillation.

Example II 109.4 g. cocoa butter, acid figure 7.8. is shaken with 7 g. allyl amine monohydrate for 20 minutes at 70 C. After centrifugation the rafiinate layer is washed out with water and dried, after which a product with an acid figure of 0.57 is obtained.

Example III 125 g. palm oil,'acid figure 10.3, is shaken for 20 minutes at 35-40 C. with 15 g. of a solution prepared by saturating cm of distilled water at room temperature with trimethyl amine. The mixture is subsequently centrifuged, the rafilnate layer is washed and dried, an oil with an acid figure of 0.43 being thus obtained.

Example I V' 50 g. cocoa butter with acid figure=7.8 was shaken for 20 minutes witha solution of 1.5 g. water in 8.5 g. benzyl amine at 60 C. The mixture was subsequently centrifuged for minutes. The oil layer was decanted from the dark brown extract layer and washed out with water until it remained neutral. After drying a refined cocoa butter with acid figure=0.92 was obtained.

Example V 50 g. cocoa butter with acid figure='7.8 was shaken for 20 minutes at 60 C. with a solution of 0.9 g. water in 5.1 g. cadaverine (pentamethylene diamine). On centrifugation the rafiinate (top layer) was washed with water and then dried. The acid figure was 0.20.

These examples show clearly the superiority of our refining agents over those of the prior art. The results obtained in Example I may be compared with those obtainable with monoethanol amine, for example, which is recognized as the most successful prior vegetable oil refining agent. The same cocoa butter (acid figure 7.8) refined in the same way with 10.5 grams of monoethanol amine per 125 g, of butter yielded a product with an acid figure almost twice as high, namely about 0.20. The lower acid figures obtained by the process of our invention are the result, among other things, of the sharper separations obtainable between the extract and raffinate phases when using hydrated amines as refining agents. Where the separation is incomplete and extract remains in the oil in a finely divided state stabilized by amine soaps, water washing hydrolyzes the soap and liberates acid which dissolves in the oil and raises the acid figure. Hydrated amines, particularly ethylene diamine monohydrate, have a smaller emulsifying capacity and solubility for ester type oils than those of mono-ethanol amine. The lower amidation'losses occur in the process of our invention. The great difference in boiling point of the lower hydrated amines as compared with mono-ethanol'amine gives them particular advantages with respect to ease of recovery and risk of amidation.

' It is thus evident that our invention offers many advantages over prior methods of refining animal and vegetable oils, fats and waxes. It is highly flexible and may be carried out in many difi'erent ways without departing from the spirit of our invention which is not to be regarded as limited to the details of operation disclosed or by the theories advanced in explanation of the improved results attained, but only by the terms of the accompanying claims in which it is our intention to claim all novelty inherent therein as broadly as possible in view of the prior art.

We claim as our invention:

1. In a process of purifying a substance of the class consisting of oils, fats and waxes oi. the ester type, the step which comprises contacting said substance with a hydrated amine of the class consisting of aliphatic and aralkyl amines free from hydroxyl groups.

2. In a process of purifying a substance of the class consisting of oils, fats and waxes of the ester type, the step ,which comprises contacting said substance with a mixture of arramine of the class consisting of aliphatic and aralykyl amines without hydroxyl groups and sufiicient water to render said amine substantially insoluble in said substance.

3. A process of purifying a substance of the class consisting of oils. fats and waxes or the ester type which comprises extracting impurities from said substance in the liquid state with a liquid mixture comprising anamine of the class consisting of aliphatic and aralkyl amines having no hydroxyl groups in the molecule together with sufllcient water to cause the formation of two substantially unemulsified liquid phases when in contact with said substance.

4. In a process of purifying a substance of the class consisting of oils, fats and waxes oi the ester type, the step which comprises contacting said substance with a'mixture comprising an amine of the class consisting of aliphatic and aralkyl amines without hydroxyl groups and about 1 to about 2 molecules of water per molecule of said amine.

5. The process of purifying a substance of the class consisting of, oils, fats and waxes of the ester type which comprises extracting impurities from said substance by contacting it with a mixture comprising an amine of the class consisting of aliphatic and aralkyl amines without hydroxyl groups and about 1 to about 2 molecules of water substance being treated and water washing the latter.

7. The process of purifying a substance of the class consisting of oils, tats and waxes of the ester type which comprises extracting impurities.

from said substance bycontacting it with a mixture comprising an amine of the class consisting of aliphatic and aralkyl amines without hydroxyl groups and about 1 to about 2 molecules of water per molecule of said amine, separating said amine containing extracted impurities from the substance being treated and recovering amine from the extract by distillation.

8. A continuous process of purifying a substance of the class consisting of oils, fats andwaxes of the ester type which comprises treating a continuous flow of the substance to be purified in the liquid state with a liquid mixture comprising an amine of the class consisting of aliphatic and aralkyl amines without hydroxyl groups and about 1 to about 2 molecules of water per molecule of said amine, separating said amine containing extracted impurities from the substance being treated and recovering the amine and returning it together with water in said proportions to the said substance in the liquid phase with a liquid mixture comprising an aliphatic amine having no hydroxyl groups in the molecule and about it to about 2 molecules of water per molecule of said amine.

10. In a process of purifying a substance of the class consisting of oils, fats and waxes of the ester type, the step whichcomprises contacting said substance in the liquid phase with a prly amine without hydroxyl groups and about 1 to about 2 molecules of water per molecule of said amine.

11. In a process of purifying a substance of the class consisting of oils, fats and waxes of the ester type, the step which comprises contacting said substance in the liquid phase with. a liquid mixture comprising an alkylene polyamine and about 1 to about 2 molecules of water per molecule of said amine.

12. In a process of purifying a substance of the class consisting of oils, fats and waxes of the ester type, the step which comprises contacting said substance in the liquid phase with a liquid mixture comprising a diamine and about 1 to about 2 molecules of water per molecule of said amine.

13. In a process of purifying a substance of the class consisting of oils, fats and waxes of the ester type, the step which comprises contacting said substance in the liquid phase with a liquid mixture comprising ethylene diamine monohydrate.

14. In a process of purifying cocoa butter the step of contacting the cocoa butter at a temperature below about 100 C. with a liquid mixture of ethylene diamine and water in the proportions of about 1 to about 2 molecules of water per molecule of ethylene diamine.

. SIEGFRIED LEONARD LANGEDIJK.

WILLEM COLTOF. 

